An Electro Luminescence (EL) display device utilizing EL of a light emitting material has been focused on as a display device having a greater response speed and a greater viewing angle than a liquid crystal display device.
Such a display device includes, for example, a Thin Film Transistor (TFT) substrate including a TFT provided on a support body including a glass substrate or the like, and a light emitting element such as an OLED element provided on the TFT substrate and connected to the TFT.
However, since such a light emitting element is generally susceptible to moisture, oxygen or the like, reaction of the light emitting element with a small amount of moisture or oxygen deteriorates properties of the light emitting element, and impairs a life of a display device.
Accordingly, to prevent moisture or oxygen from entering the light emitting element, there is known, for example, a Thin Film Encapsulation (TFE) technique of sealing a light emitting element with a sealing film formed on the light emitting element and including inorganic layers and organic layers alternately layered one on another (for example, see PTL 1 and PTL 2).
An inorganic layer has a moisture prevention function to prevent entrance of moisture, and functions as a barrier layer. On the other hand, an organic layer is used as a buffer layer (stress release layer) to mainly release stress of the inorganic layer and to level a display region by eliminating a step on a surface of a light emitting element layer including the light emitting element.
For example, Chemical Vapor Deposition (CVD) is used for forming a film of the inorganic layer, and for example, an ink-jet method is used for forming a film of the organic layer (for example, see PTL 2).